In order to determine whether celastrol inhibits the STAT3 signaling pathway in NSCLC cells by ROS mediation, we tested STAT3 phosphorylation levels under different treatment conditions by Western blot, and the results showed that the antioxidant NAC could reverse the inhibitory effect of celastrol on the STAT3 signaling pathway. This evidence concerns the gene STAT3 and non-small cell lung carcinoma.